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ZVC403 doesn't work as designed for me

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jrkeat
jrkeat Member Posts: 71
edited June 2020 in Thermostats and Controls
I'm redoing my boiler, and am re-using a set of three Taco ZV403-4 controllers, and some Honeywell V8043E1012 zone valves.

When I use the zone control lines from the Taco (as the installation instructions suggest), they don't open the valve in some cases. Sometimes they work. Sometimes they take a long time to open. Sometimes they just sit in place. My Erie pop top hums and never moves. I think the Taco zone valve lines must be a bit under powered.

I notices the person who originally used the valves with these controllers wired the valve motors to the thermostat lines. That would work, though it would be a bit of a pain at this point. I thought it was bizarre when I pulled them out, but maybe it's the right way to use them.

Is there some way to get it work as the wiring diagram in the ZV403 would suggest, or should I give up an run the motors off the thermostats?

Comments

  • Zman
    Zman Member Posts: 7,569
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    The Taco controller normally works perfectly with the Honeywell valves. How old are the valves? How many volts is the controller putting out under load?
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • jrkeat
    jrkeat Member Posts: 71
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    The zone motor voltage is 19.6 loaded when the motor doesn't move, and 24.0V when it does. The valves are maybe 15 years old. They all run fine if you connect them directly to the the 24V on the thermostat side.
  • jrkeat
    jrkeat Member Posts: 71
    edited June 2020
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    Also, one of the ZV403s works better than the other two to control the valves. Two of them basically don't work at all. The voltages are from one of the ones that mostly doesn't work.
  • Ironman
    Ironman Member Posts: 7,376
    edited June 2020
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    Do you have more than 6 zones valves? If not, why so many zone controls?

    Have you observed the VA requirements for each valve and then compared the total VA that the zone control can handle? An additional transformer(s) is necessary if the VA draw of all the valves exceeds the 80% of the VA rating of the transformer in the ZVC.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • jrkeat
    jrkeat Member Posts: 71
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    There are 7 zones. The 403s do 3 zones each.

    The valves are listed as 7.7VA, so 23VA total. The controller is rated at 40VA, so they shouldn't have a problem. And that's clearly not the issue here, as I'm just testing one valve at a time.
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,519
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    Agree with @Ironman

    Sounds like you losing power or have an overloaded transformer.

    Normally valves and other equipment should be powered within 10% of the rated voltage.24-10%=21.6

    I have seen this before you get down around 20 volts things get flaky
  • unclejohn
    unclejohn Member Posts: 1,833
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    Did you wire them right. Red wires are end switch and yellow is motor. I think. Can you take picture or draw out how one valve is wired to the controller.
  • Hilly
    Hilly Member Posts: 427
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    Could fancy new thermostats be stealing power?
  • jrkeat
    jrkeat Member Posts: 71
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    There are no fancy thermostats.

    Another interesting tidbit: The zone 3s can supply more power, and will operate all the valves.
  • Jamie Hall
    Jamie Hall Member Posts: 23,280
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    You may also have a bad connection somewhere in the wiring. It wouldn't take all that many ohms in a bad connection to drop the voltage like that.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • jrkeat
    jrkeat Member Posts: 71
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    The more I look at it, it seems like a design problem with a particular board. The board that works has a "3" in the lower middle left, while the two bad ones have a "2".

    I'm only running one zone off of one of the two bad ones so I can use the good zone 3 for that, and I only have to rewire two zones one board to use the thermostats to run the motors.
  • ratio
    ratio Member Posts: 3,625
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    If that's the case, maybe Taco has a recall or ECO for that revision. Worth a call to tech support, I think.
  • Zman
    Zman Member Posts: 7,569
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    jrkeat said:

    The zone motor voltage is 19.6 loaded when the motor doesn't move, and 24.0V when it does. The valves are maybe 15 years old. They all run fine if you connect them directly to the the 24V on the thermostat side.

    I am curious what voltage you are seeing going in? 120?
    Are you saying that the motor works when you run it off the t-stat side of the taco? Same transformer? If so, I would say you have a bad relay or a smoked board.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Zman
    Zman Member Posts: 7,569
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    @Joe Mattiello May be checking in from TACO....
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • unclejohn
    unclejohn Member Posts: 1,833
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    It for sure is not a design problem.
    ZmanSuperTech
  • Zman
    Zman Member Posts: 7,569
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    With existing equipment, you always have to wonder if someone before you wired it backwards and let some of the smoke out. :(
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
    kcopp
  • jrkeat
    jrkeat Member Posts: 71
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    Zman said:

    jrkeat said:

    The zone motor voltage is 19.6 loaded when the motor doesn't move, and 24.0V when it does. The valves are maybe 15 years old. They all run fine if you connect them directly to the the 24V on the thermostat side.

    I am curious what voltage you are seeing going in? 120?
    Are you saying that the motor works when you run it off the t-stat side of the taco? Same transformer? If so, I would say you have a bad relay or a smoked board.
    122V going in.

    I decided to wire around the problem.

    Basically zones 1 and 2 weren't working well enough (19V out under load) on two of the boards.

    That meant 5 of the 9 zones work correctly, and I need 7.

    I used those 5 zones and wired the other two motors "across" the board, so they take their voltage directly from the thermostat. I'll write a note for the next person who looks at it.


  • SteveSan
    SteveSan Member Posts: 234
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    Please confirm your wiring to the attach picture. You can always call into Taco Tech Support at 401-942-8000 and just ask for Tech Support. We are available Mon-Fri 8am-5pm EST.

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